Displays with flipped panel structures

ABSTRACT

A display may have a thin-film transistor layer and a color filter layer. The display may include light blocking structures formed on a transparent substrate. In one arrangement, a clear planarization layer may be formed over the light blocking structures. The thin-film transistor layer may be formed over the planarization layer. The color filter layer may be integrated with the thin-film transistor layer. At least light blocking structures and the planarization layer should be formed from high temperature resistance material. In another arrangement, the color filter layer may be formed on the light blocking structures. A clear planarization layer may then be formed over the color filter layer. The thin-film transistor layer may be formed on the planarization layer. In this arrangement, the color filter layer also needs to be formed from thermal resistance material.

This application claims the benefit of provisional patent applicationNo. 61/935,734, filed Feb. 4, 2014, which is hereby incorporated byreference herein in its entirety.

BACKGROUND

This relates generally to electronic devices and, more particularly, toelectronic devices with displays.

Electronic devices often include displays. For example, cellulartelephones, computers, and televisions have displays.

A display such as a liquid crystal display has an active area filledwith an array of display pixels. The active area is surrounded by aninactive border area. It may be desirable to minimize or eliminate theuse of unsightly bezel structures in the inactive border area. Indisplays with small bezels or no bezels, there is a risk that backlightcan leak through the inactive border area. If care is not taken, straybacklight will undesirably lighten the inactive area.

It would therefore be desirable to be able to provide improved lightblocking structures in displays such as liquid crystal displays.

SUMMARY

An electronic device having a liquid crystal display (LCD) is provided.The liquid crystal display may include display pixel circuitry formed ona glass substrate. Light blocking structures such as black maskingmaterial may be patterned on the glass substrate to prevent stray lightfrom propagating in undesired directions.

In one suitable arrangement, a planarization layer may be formed on theglass substrate over the light blocking structures. Thin film transistorstructures such as thin-film transistors and associated pixel electrodesmay be formed over the planarization layer. A color filter layer may beinterposed between the thin-film transistors and the pixel electrodes(e.g., color filter elements may be integrated with the thin-filmtransistor structures). If desired, additional light blocking structuresmay be embedded with the color filter layer (e.g., additional lightblocking structures may be formed directly on respective color filterelements). Liquid crystal material may be formed over the color filterlayer. Formed in this way, at least the light blocking structures formedon the glass substrate and the planarization layer may be formed fromhigh temperature resistant material (e.g., material that can withstandtemperatures of at least 300° C. without degrading).

Display circuitry of this type may be assembled in a flippedorientation. Configured in the flipped orientation, a backlight unit inthe LCD display may emit backlight that travels through the liquidcrystal material, the color filter layer, the thin-film transistorstructures, the planarization layer, and the glass substrate in thatorder to a user of the electronic device.

In another suitable arrangement, a color filter array may be formeddirectly on the glass substrate over the light blocking structures. Aplanarization layer may be formed on the color filter array. A thin-filmtransistor (TFT) layer may then be formed on the planarization layer. Ifdesired, additional light blocking structures may be embedded within thethin-film transistor layer (e.g., additional black mask material may beformed directly on one or more dielectric layers directly abovethin-film transistors in the TFT layer). Liquid crystal material may beformed over the thin-film transistor layer. Formed in this way, at leastthe light blocking structures formed on the glass substrate, the colorfilter array, and the planarization layer may be formed from highthermal resistant material (e.g., material that can withstandtemperatures of at least 300° C. without degradation).

Display circuitry of this type may also be assembled in a flippedorientation. Configured in the flipped/inverted orientation, a backlightunit in the LCD display may emit backlight that travels through theliquid crystal material, the thin-film transistor layer, theplanarization layer, the color filter array, and the glass substrate inthat order to a user of the electronic device.

Further features of the present invention, its nature and variousadvantages will be more apparent from the accompanying drawings and thefollowing detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an illustrative electronic device suchas a laptop computer with a display in accordance with an embodiment.

FIG. 2 is a perspective view of an illustrative electronic device suchas a handheld electronic device with a display in accordance with anembodiment.

FIG. 3 is a perspective view of an illustrative electronic device suchas a tablet computer with a display in accordance with an embodiment.

FIG. 4 is a perspective view of an illustrative electronic device suchas a display for a computer or television with a display in accordancewith an embodiment.

FIG. 5 is a cross-sectional side view of an illustrative display inaccordance with an embodiment.

FIG. 6 is a cross-sectional side view of a portion of an illustrativeelectronic device showing how an edge of a display in the device may befree of overlapping housing structures in accordance with an embodiment.

FIG. 7 is a cross-sectional side view of display circuitry having colorfilter elements interposed between thin-film transistor structures andliquid crystal material in accordance with an embodiment.

FIG. 8 is a cross-sectional side view of display circuitry havingthin-film transistor structures interposed between liquid crystalmaterial and color filter elements in accordance with an embodiment.

FIG. 9 is a more detailed view of the display circuitry of FIG. 7 inaccordance with an embodiment.

FIG. 10 is a more detailed view of the display circuitry of FIG. 8 inaccordance with an embodiment.

DETAILED DESCRIPTION

Illustrative electronic devices of the types that may be provided withdisplays are shown in FIGS. 1, 2, 3, and 4.

Electronic device 10 of FIG. 1 has the shape of a laptop computer andhas upper housing 12A and lower housing 12B with components such askeyboard 16 and touchpad 18. Device 10 has hinge structures 20(sometimes referred to as a clutch barrel) to allow upper housing 12A torotate in directions 22 about rotational axis 24 relative to lowerhousing 12B. Display 14 is mounted in housing 12A. Upper housing 12A,which may sometimes be referred to as a display housing or lid, isplaced in a closed position by rotating upper housing 12A towards lowerhousing 12B about rotational axis 24.

FIG. 2 shows an illustrative configuration for electronic device 10based on a handheld device such as a cellular telephone, music player,gaming device, navigation unit, or other compact device. In this type ofconfiguration for device 10, housing 12 has opposing front and rearsurfaces. Display 14 is mounted on a front face of housing 12. Display14 may have an exterior layer that includes openings for components suchas button 26 and speaker port 28. Device 10 may, if desired, be acompact device such as a wrist-mounted device or pendant device (asexamples).

In the example of FIG. 3, electronic device 10 is a tablet computer. Inelectronic device 10 of FIG. 3, housing 12 has opposing planar front andrear surfaces. Display 14 is mounted on the front surface of housing 12.As shown in FIG. 3, display 14 has an opening to accommodate button 26.

FIG. 4 shows an illustrative configuration for electronic device 10 inwhich device 10 is a computer display, a computer that has an integratedcomputer display, or a television. Display 14 is mounted on a front faceof housing 12. With this type of arrangement, housing 12 for device 10may be mounted on a wall or may have an optional structure such assupport stand 30 to support device 10 on a flat surface such as a tableor desk.

Display 14 may be a liquid crystal display or a display formed usingother suitable display technologies. A cross-sectional side view of anillustrative configuration for display 14 of device 10 (e.g., a liquidcrystal display for the devices of FIG. 1, FIG. 2, FIG. 3, FIG. 4 orother suitable electronic devices) is shown in FIG. 5. As shown in FIG.5, display 14 may include backlight structures such as backlight unit 42for producing backlight 44. During operation, backlight 44 travelsoutwards (vertically upwards in dimension Z in the orientation of FIG.5) and passes through display pixel structures in display layers 46.This illuminates any images that are being produced by the displaypixels for viewing by a user. For example, backlight 44 may illuminateimages on display layers 46 that are being viewed by viewer 48 indirection 50.

Display layers 46 may be mounted in chassis structures such as a plasticchassis structure and/or a metal chassis structure to form a displaymodule for mounting in housing 12 or display layers 46 may be mounteddirectly in housing 12 (e.g., by stacking display layers 46 into arecessed portion of housing 12).

Display layers 46 may include a liquid crystal layer such a liquidcrystal layer 52. Liquid crystal layer 52 may be sandwiched betweendisplay layers such as display layers 58 and 56. Layers 56 and 58 may beinterposed between lower (innermost) polarizer layer 60 and upper(outermost) polarizer layer 54.

Layers 58 and 56 may be formed from transparent substrate layers such asclear layers of glass or plastic. Layers 56 and 58 may be layers such asa thin-film transistor layer and/or a color filter layer. Conductivetraces, color filter elements, transistors, and other circuits andstructures may be formed on the substrates of layers 58 and 56 (e.g., toform a thin-film transistor layer and/or a color filter layer). Touchsensor electrodes may also be incorporated into layers such as layers 58and 56 and/or touch sensor electrodes may be formed on other substrates.

With one illustrative configuration, outer substrate layer 56 may be athin-film transistor layer that includes an array of thin-filmtransistors and associated electrodes (display pixel electrodes) forapplying electric fields to liquid crystal layer 52 and therebydisplaying images on display 14. Inner substrate layer 58 may be a colorfilter layer that includes an array of color filter elements forproviding display 14 with the ability to display color images.

In another suitable arrangement, inner substrate layer 58 may be athin-film transistor layer that includes an array of thin-filmtransistors and associated electrodes (display pixel electrodes) forapplying electric fields to liquid crystal layer 52, whereas outersubstrate layer 56 may be a color filter layer that includes an array ofcolor filter elements for providing display 14 with the ability todisplay color images.

Backlight structures 42 may include a light guide plate such as lightguide plate 78. Light guide plate 78 may be formed from a transparentmaterial such as clear glass or plastic. During operation of backlightstructures 42, a light source such as light source 72 may generate light74. Light source 72 may be, for example, an array of light-emittingdiodes.

Light 74 from light source 72 may be coupled into edge surface 76 oflight guide plate 78 and may be distributed in dimensions X and Ythroughout light guide plate 78 due to the principal of total internalreflection. Light guide plate 78 may include light-scattering featuressuch as pits or bumps. The light-scattering features may be located onan upper surface and/or on an opposing lower surface of light guideplate 78.

Light 74 that scatters upwards in direction Z from light guide plate 78may serve as backlight 44 for display 14. Light 74 that scattersdownwards may be reflected back in the upwards direction by reflector80. Reflector 80 may be formed from a reflective material such as alayer of white plastic or other shiny materials.

To enhance backlight performance for backlight structures 42, backlightstructures 42 may include optical films 70. Optical films 70 may includediffuser layers for helping to homogenize backlight 44 and therebyreduce hotspots, compensation films for enhancing off-axis viewing, andbrightness enhancement films (also sometimes referred to as turningfilms) for collimating backlight 44. Optical films 70 may overlap theother structures in backlight unit 42 such as light guide plate 78 andreflector 80. For example, if light guide plate 78 has a rectangularfootprint in the X-Y plane of FIG. 5, optical films 70 and reflector 80may have a matching rectangular footprint.

Display 14 may have an array of display pixels (e.g., a rectangulararray having rows and columns) for displaying images to a viewer.Vertical signal lines called data lines may be used to carry displaydata to respective columns of display pixels. Horizontal signal linescalled gate lines may be used to carry gate line signals (sometimesreferred to as gate control signals or gate signals) to respective rowsof display pixels. The outline of the array of display pixels in display14 defines an active area for display 14. The active area may have arectangular shape and may be surrounded by an inactive border region. Aninactive border area may, for example, run along one edge, two edges,three edges, or all four edges of the active area.

A cross-sectional side view of an illustrative electronic device havinga display such as display 14 of FIG. 5 is shown in FIG. 6. As shown inFIG. 6, images may be displayed on central active area AA of display 14.Inactive area IA may have a rectangular ring shape that runs around therectangular periphery of active area AA. To avoid unsightly bezelstructures in device 10, it may be desirable to keep inactive area IAfree of overlapping housing structures, bezels, or other potentiallyunattractive border structures.

To avoid light leakage in inactive area IA (e.g., to prevent stray lightfrom escaping in the absence of a bezel or other overlapping structure),display 14 may be provided with border masking structures in inactivearea IA. The border masking structures may help block stray backlightfrom backlight unit 42 and thereby ensure that border IA does not allowexcess light to escape. Backlight from backlight unit 42 will thereforebe confined to active area AA.

To provide satisfactory light blocking capabilities, light blockingstructures can be formed in two parts (e.g., two layers). A first partof the light blocking structures may be formed from a black maskinglayer on the underside of thin-film transistor layer 56. The blackmasking layer may be patterned to form a black mask. The black mask is agrid-shaped series of intersecting black lines that define a rectangulararray of clear display pixel openings in the thin-film transistor layer.Each of the openings in the black mask is aligned with a respectivecolor filter element in a corresponding array of color filter elementson color filter layer 58. The grid-shaped black mask on the thin-filmtransistor layer may sometimes be referred to as a black matrix. Asecond part of the light blocking structures may be formed from opaquestructures that are integrated with color filter layer 58. The first andsecond parts of the light blocking structures may be at least partlyoverlapping to ensure that light emitted from each image pixel does notleak into undesired regions on the display (e.g., to ensure that thelight associated with a given display pixel does not leak into anadjacent pixel location or into the inactive area).

FIG. 7 shows a cross-sectional side view of illustrative displaycircuitry 100 that can be formed as part of device 10. As shown in FIG.7, display circuitry 100 may include a first transparent substrate suchas substrate 102-1. Substrate 102-1 may be formed from a clear planarstructure such as a sheet of transparent plastic, transparent glass, orother clear substrate layer. Black masking layer 106 may be patterned toform part of a black matrix in active area AA of the display and may bepatterned to form part of a light-blocking black mask border in inactivearea IA.

Black masking material 106 may be formed from a photoimageable materialsuch as black photoresist. The black photoresist may be formed from apolymer such as polyimide. To withstand the elevated temperaturesinvolved in subsequent thin-film transistor fabrication steps, thepolymer that is used in forming black masking material 106 preferablycan withstand elevated temperatures (e.g., temperatures of 350° C. orhigher or other suitable elevated temperatures). Opaque filler materialssuch as carbon black and/or titanium black may be incorporated into thepolyimide or other polymer of layer 106 so that layer 106 is opaque.

Planarization layer 104 is used to planarize black masking layer 106 sothat thin-film transistor circuitry 106 can be formed over black maskinglayer 106 (e.g., so that thin-film transistors can overlap black mask106). As an example, planarization layer 104 is formed from a black maskcompatible material having a low dielectric constant such as a spin-onglass (SOG). For example, planarization layer 104 may be formed from aspin-on glass such as a silicon oxide based spin-on glass (e.g., asilicate spin-on glass). During thin-film transistor formation, thestructures of FIG. 7 may be subjected to elevated processingtemperatures (e.g., temperatures of 350° C. or higher). Polyimide blackmask layer 106 and spin-on glass planarization layer 104 are preferablyable to withstand processing at these elevated temperatures (i.e.,spin-on glass layer 104 will not experience diminished transparency andpolyimide layer 106 will not degrade).

Thin-film transistor (TFT) structures 110 may be formed on planarizationlayer 104. For example, one or more thin-film transistors and/ortransistors associated with gate driver circuitry may be formed onplanarization layer 104 as part of layer 110. As described above, it maybe desirable to form the thin-film transistors at locations overlappingwith black masking layer 106. In general, regions in layer 110 that arenot overlapping with any black mask material 106 should be devoid ofthin-film transistors.

An array of color filter elements 108 may be formed over the TFTstructures 110. Color filter elements 108 may include red color filterelements R, blue color filter elements B, and green color filterelements G. Color filter elements 108 may be formed from low-k coloredphotoimageable polymers. In other words, color filter elements 108 maybe formed from organic material having a dielectric constant K less thanthat of silicon dioxide. The use of low-k color filter elementseliminates the need for an additional clear overcoat layer to bedisposed directly on the thin-film transistors, which can help improvebacklight transmittance.

Each color filter element 108 in the array of color filter elements maybe laterally aligned with a respective opening in the array of openingsin the black matrix formed from material 106 within the planarizationlayer 104 (e.g., each display pixel in the display may have atransparent opening, an associated display pixel electrode, and anassociated aligned color filter element 108 through which backlight canpass). In the example of FIG. 7, black mask material 116 may also beembedded within the array of color filter elements 108. Black maskmaterial 116 may be at least partially aligned with black mask material106.

Color filter elements 108 formed in this way may be considered to beintegrated with the thin-film transistor structures. Configured in thisway, color filter elements 108 merely serve as one of the dielectriclayers that are formed over the thin-film transistors. Other displaypixel structures such as the pixel electrode, the common electrode, andother pixel interconnect routing structure can actually be formed overcolor filter elements 108. Integrating the color filter elements withthe formation of the thin-film transistors enables both the thin-filmtransistor structures and the color filter elements to be manufacturingat the same fabrication facility without the need for an additionalcolor filter to TFT assembly process. Moreover, the required width ofblack mask material 116 can also be reduced, since the distance betweenmaterials 106 and 116 is minimized by forming the color filter elementsdirectly on the thin-film transistors.

This arrangement in which the color filter elements are integrated withthe thin-film transistor layer is sometimes referred to as thecolor-filter-on-array or “COA” configuration. The thin-film transistorstructures 110 and the integrated color filter elements 108 maytherefore sometimes be referred to collectively as a COA layer 112.Still referring to FIG. 7, liquid crystal (LC) material 114 may beformed on COA layer 112. A second transparent substrate such assubstrate 102-2 (e.g., a sheet of transparent plastic, transparentglass, or other clear substrate layer) may be formed over the liquidcrystal material 114.

The orientation of circuitry 100 in FIG. 7 is actually inverted forillustrative purposes. During operation of device 10, the backlighttravels in direction Z and passes through display pixel structures andcolor filter elements in circuitry 100. From a users perspective (e.g.,FIG. 5 a user 48 that looks at display 14 from the top), the COA layeris formed over the liquid crystal material 114 (i.e., the color filterelements 108 are formed over LC material 114, whereas the thin-filmtransistors are formed over the color filter elements 108). Displaycircuitry 100 oriented in this way may sometimes be referred to as aflip-over display panel or a flipped TFT panel (sometimes abbreviated asFTP).

The example of FIG. 7 in which the color filter elements are interposedbetween the liquid crystal material and the thin-film transistors ismerely illustrative and does not serve to limit the scope of the presentinvention. FIG. 8 shows another suitable arrangement in which thethin-film transistors are interposed between the liquid crystal materialand the color filter elements. As shown in FIG. 8, display circuitrysuch as display circuitry 200 may include a first transparent substratesuch as substrate 202-1. Substrate 202-1 may be formed from a clearplanar structure such as a sheet of transparent plastic, transparentglass, or other clear substrate layer. Black masking layer 206 may bepatterned to form part of a black matrix in active area AA of thedisplay and may be patterned to form part of a light-blocking black maskborder in inactive area IA.

Black masking material 206 may be formed from a photoimageable materialsuch as black photoresist (e.g., polyimide). To withstand the elevatedtemperatures involved in subsequent thin-film transistor fabricationsteps, the polymer that is used in forming black masking material 206preferably can withstand elevated temperatures (e.g., temperatures of300° C. or higher or other suitable elevated temperatures). Opaquefiller materials such as carbon black and/or titanium black may beincorporated into the polyimide or other polymer of layer 206 so thatlayer 206 is opaque.

In particular, an array of color filter elements 208 may be formed onsubstrate 202-1 over black masking material 206. Color filter elements208 may include red color filter elements R, blue color filter elementsB, and green color filter elements G. Color filter elements 208 may beformed from colored photoimageable polymers.

Planarization layer 208 is used to planarize color filter elements 204so that thin-film transistor circuitry 210 can be formed over colorfilter layer 204 (e.g., so that thin-film transistors can overlap blackmask 206). As an example, planarization layer 204 is formed from a blackmask compatible material having a low dielectric constant such as aspin-on glass (SOG). For example, planarization layer 204 may be formedfrom a spin-on glass such as a silicon oxide based spin-on glass (e.g.,a silicate spin-on glass). During thin-film transistor formation, thestructures of FIG. 8 may be subjected to elevated processingtemperatures (e.g., temperatures of 350° C. or higher). Polyimide blackmask layer 206, color filter elements 204, and spin-on glassplanarization layer 208 are preferably able to withstand processing atthese elevated temperatures (i.e., spin-on glass layer 208 will notexperience diminished transparency, and color filter elements 204 andpolyimide layer 206 will not degrade).

Thin-film transistor (TFT) structures 210 may be formed on planarizationlayer 208. For example, one or more thin-film transistors and/ortransistors associated with gate driver circuitry may be formed onplanarization layer 208 as part of layer 210. As described above, it maybe desirable to form the thin-film transistors at locations overlappingwith black masking layer 206. In general, regions in layer 210 that arenot overlapping with any black mask material 206 should be devoid ofthin-film transistors and should be laterally aligned with a respectiveopening in the array of openings in the black matrix formed frommaterial 206 and with each respective color filter element 204.

In the example of FIG. 8, black mask material 212 may also be embeddedwithin the TFT layer 210. Black mask material 212 may be at leastpartially aligned with black mask material 206. The required width ofblack mask material 212 can be minimized by reducing the distancebetween materials 206 and 212 (e.g., by forming the black mask material212 on dielectric layers relatively close to the thin-film transistors).

Forming display circuitry 200 in this way allows the thin-filmtransistor layer and the color filter array to be manufacturing at thesame fabrication facility without the need for an additional colorfilter to TFT assembly process. This arrangement in which the thin-filmtransistor layer is formed on the color filter layer is sometimesreferred to as the array-on-color-filter or “AOC” configuration. Stillreferring to FIG. 8, liquid crystal (LC) material 214 may be formed onTFT layer 210. A second transparent substrate such as substrate 202-2(e.g., a sheet of transparent plastic, transparent glass, or other clearsubstrate layer) may be formed over the liquid crystal material 214.

The orientation of circuitry 200 in FIG. 8 is actually flipped forillustrative purposes. During operation of device 10, the backlighttravels in direction Z and passes through display pixel structures andcolor filter elements in circuitry 200. From a users perspective (e.g.,FIG. 5 a user 48 that looks at display 14 from the top), the colorfilter elements 204 are formed over the thin-film transistors, whereasthe thin-film transistors are formed over the LC material 214. Displaycircuitry 200 oriented in this way may also be considered an FTPdisplay.

FIG. 9 shows a more detailed cross-sectional side view of displaycircuitry 100 described in connection with FIG. 7. As shown in FIG. 9,display circuitry 100 may include a transparent thin-film transistorsubstrate such as substrate 300 (similar to substrate 102-1 of FIG. 7).Substrate 300 may be formed from a clear planar structure such as asheet of transparent plastic, transparent glass, or other clearsubstrate layer. Black masking layer 302 may be patterned to form ablack matrix in active area AA of display 14 and may be patterned toform part of a light-blocking black mask border in inactive area IA.

As shown in FIG. 9, black masking layer 302 may be patterned to formdisplay pixel openings such as opening 304 that are aligned withpatterned display pixel electrodes 310. Electrodes 310 may be separatedfrom common electrode (Vcom) trace 312 by dielectric layer 314. Colorfilter element material 350 may be formed on top of thin-film transistor324 from a photoimageable polymer or other dielectric (e.g., a colorfilter layer may be interposed between thin-film transistor 324 andassociated electrodes 310). Additional black masking material 352(similar to BM material 116 in FIG. 7) may be formed on top of colorfilter layer 350 directly over transistor 324.

Patterned metal 318 may be used to form transistor terminals such assource S, drain D, and gate G. Gate insulator 320 may be formed fromdielectric materials such as silicon nitride and/or silicon oxide andmay separate gate G from semiconductor region 322. Semiconductor region322, which is used in forming the channel region for thin-filmtransistor 324, may be formed from semiconductor materials such asamorphous silicon, polysilicon, indium gallium zinc oxide, or othersemiconductors. Passivation layer 326 may be formed on top of gateinsulator 320.

As described above in connection with FIG. 7, black masking material 302may be formed from a photoimageable material such as black photoresist(e.g., polyimide). Planarization layer 306 (e.g., a spin-on glass layer)may be used to planarize black masking layer 302. During thin-filmtransistor formation, the structures of FIG. 9 may be subjected toelevated processing temperatures (e.g., temperatures of 350° C. orhigher). Polyimide black mask layer 302 and spin-on glass planarizationlayer 306 are preferably able to withstand processing at these elevatedtemperatures (i.e., spin-on glass layer 306 will not experiencediminished transparency and polyimide layer 302 will not degrade).

In some embodiments, a buffer layer such as inorganic buffer layer 307may be formed at the interface between planarization layer 306 and TFTlayer 308. Buffer layer 307 may be a thin layer of silicon nitride,silicon oxide, and/or other inorganic materials having a thickness of250-3000 angstroms (as an example). Formed in this way, inorganic bufferlayer 307 may serve to prevent chemicals such as etching solution frombeing injected into spin-on glass planarization layer 306 duringformation of the TFT circuitry in layer 308.

FIG. 10 shows a more detailed cross-sectional side view of displaycircuitry 200 described in connection with FIG. 8. As shown in FIG. 10,display circuitry 200 may include a transparent thin-film transistorsubstrate such as substrate 400 (similar to substrate 102-1 of FIG. 8).Substrate 400 may be formed from a clear planar structure such as asheet of transparent plastic, transparent glass, or other clearsubstrate layer. Black masking layer 402 may be patterned to form ablack matrix in active area AA of display 14 and may be patterned toform part of a light-blocking black mask border in inactive area IA.

As shown in FIG. 10, black masking layer 402 may be patterned to formdisplay pixel openings such as opening 404 that are aligned withpatterned display pixel electrodes 410. Electrodes 410 may be separatedfrom common electrode (Vcom) trace 412 by dielectric layer 414.Dielectric material 416 may be formed on top of thin-film transistor 424from a photoimageable polymer or other dielectric. Additional blackmasking material 452 (similar to BM material 212 in FIG. 8) may beformed on top of dielectric material 416 directly over transistor 424.

Patterned metal 418 may be used to form transistor terminals such assource S, drain D, and gate G. Gate insulator 420 may be formed fromdielectric materials such as silicon nitride and/or silicon oxide andmay separate gate G from semiconductor region 422. Semiconductor region422, which is used in forming the channel region for thin-filmtransistor 424, may be formed from semiconductor materials such asamorphous silicon, polysilicon, indium gallium zinc oxide, or othersemiconductors. Passivation layer 426 may be formed on top of gateinsulator 420.

As described above in connection with FIG. 8, black masking material 402may be formed from a photoimageable material such as black photoresist(e.g., polyimide). Color filter material 450 (e.g., a first color filterelement 450-1 of a first color, a second color filter element of asecond color that is different than the first color, etc.) may be formedover black masking material 402. Planarization layer 406 (e.g., aspin-on glass layer) may be used to planarize color filter layer 450. Inother words, the color filter layer may be interposed between the TFTlayer and light blocking structures 402.

During thin-film transistor formation, the structures of FIG. 10 may besubjected to elevated processing temperatures (e.g., temperatures of350° C. or higher). Polyimide black mask layer 402, color filter array450, and spin-on glass planarization layer 406 are preferably highthermal resistant material that is able to withstand processing at theseelevated temperatures.

In some embodiments, a buffer layer such as inorganic buffer layer 407may be formed at the interface between planarization layer 406 and TFTlayer 408. Buffer layer 407 may be a thin layer of silicon nitride,silicon oxide, and/or other inorganic materials having a thickness of250-3000 angstroms (as an example). Formed in this way, inorganic bufferlayer 407 may serve to prevent chemicals such as etching solution frombeing injected into spin-on glass planarization layer 406 duringformation of the TFT circuitry in layer 408.

The foregoing is merely illustrative of the principles of this inventionand various modifications can be made by those skilled in the artwithout departing from the scope and spirit of the invention. Theforegoing embodiments may be implemented individually or in anycombination.

What is claimed is:
 1. Display circuitry, comprising: a transparentsubstrate; light blocking structures formed on the transparentsubstrate; a display pixel having a thin-film transistor coupled toassociated pixel electrodes, wherein the display pixel is formed overthe light blocking structures, and wherein the thin-film transistor hasa bottom gate; color filter structures interposed between the thin-filmtransistor and the pixel electrodes; and additional light blockingstructures formed over the color filter structures.
 2. The displaycircuitry defined in claim 1, wherein the light blocking structurescomprise a patterned black masking layer formed on the transparentsubstrate.
 3. The display circuitry defined in claim 1, wherein thecolor filter layer is formed from low-k color filter material.
 4. Thedisplay circuitry defined in claim 1, further comprising: aplanarization layer that is formed on the transparent substrate and thatis interposed between the light blocking structures and the thin-filmtransistor.
 5. The display circuitry defined in claim 4, wherein thelight blocking structures and the planarization layer are formed frommaterial able to withstand at least 350° C. without degrading.
 6. Thedisplay circuitry defined in claim 1, wherein the light blockingstructures comprise high temperature resistant material.
 7. The displaycircuitry defined in claim 1, further comprising: liquid crystalmaterial formed over the pixel electrodes.
 8. The display circuitrydefined in claim 1, wherein the light blocking structures comprisesblack masking material.
 9. The display circuitry defined in claim 8,wherein the black masking material comprises black photoresist.
 10. Anelectronic device, comprising: a transparent substrate; light blockingstructures formed on the transparent substrate; liquid crystal material;color filter elements interposed between the liquid crystal material andthe light blocking structures, wherein the color filter elements and thelight blocking structures are formed in different layers; and abacklight unit that emits backlight, wherein the emitted backlighttravels through the color filter elements before travelling through thetransparent substrate.
 11. The electronic device defined in claim 10,wherein the emitted backlight travels through the liquid crystalmaterial before travelling through the color filter elements.
 12. Theelectronic device defined in claim 10, further comprising: a thin-filmtransistor that is interposed between the color filter elements and thelight blocking structures.
 13. The electronic device defined in claim10, further comprising: a thin-film transistor layer that is interposedbetween the color filter elements and the liquid crystal material. 14.The electronic device defined in claim 13, wherein the emitted backlighttravels through the thin-film transistor layer before travelling throughthe color filter elements.
 15. The electronic device defined in claim10, further comprising: additional light blocking structures that areformed between the transparent substrate and the liquid crystal materialand that are at least partially overlapping with the light blockingstructures formed on the transparent substrate.